Pressure reducing device

ABSTRACT

A pressure reducing valve for nasal supplying of a flow of air to a patient. The valve comprises a hollowed tubular member ( 1 ) comprising a high pressure air inlet end part ( 3 ), a low pressure air outlet end part ( 4 ) opposite to said inlet end part ( 3 ), and an intermediate air venting part having perforations ( 6, 7 ) for venting a constant and non-adjustable pressure and flow of air from the inner cavity of the tubular member ( 1 ) into the ambient atmosphere. A shielding member (FIG.  3 ) positioned above said perforations ( 6, 7 ) secures the perforations ( 6, 7 ) from becoming obstructed and for directing the air flow from said perforations ( 6, 7 ) towards said air inlet end part ( 3 ).

FIELD OF THE INVENTION

The present invention relates to a pressure-reducing valve forinstallation in connection with an air/gas-conveying conduit. Ingeneral, the valve according to the present invention is adapted tosignificantly reduce the conveyed gas pressure by splitting a suppliedstream of gas into more streams of gas. In particular, the inventionrelates to a pressure-reducing valve for nasal continuous positiveairway pressure (CPAP) treatment on premature babies.

BACKGROUND OF THE INVENTION

CPAP is an airway treatment wherein a slight positive air pressure isapplied to the respiratory organs of a patient in order to increase thevolume of inhaled air and thus, to decrease the work of breathing. CPAPtreatment is given through a set of nasal prongs, through a mask orthrough a ventilation tube fixed in the trachea. Often, neonates, inparticular premature babies, are given CPAP treatment in order torelieve the respiratory organs. Moreover, CPAP treatment is applied forthe alleviation of snoring and obstructive sleep apnea. The applied airpressure should typically not exceed the equivalence of a 2-7 cm watercolumn and the applied amount of air should not exceed the range of 5-7litres per minute. Standard gas supplies are normally adapted to delivergas of a much higher pressure and quantity and therefore a reductionvalve is inserted between the gas supply and the CPAP treating device.

In general, valves for reducing air pressure and delivered airquantities, e.g. in connection with CPAP treatment, exist. Typically, asupplied stream of air, e.g. air supplied with 6-7 bar overpressure, issplit into more streams of air. One of the streams is guided through oneoutlet to respiratory means, e.g. a set of nasal prongs or to a mask,and thus to the respiratory organs of the treated individual. The excessstream or streams of air is/are guided through other outlets to theambient atmosphere. By splitting the 6-7 bar over-pressurised stream ofair into several streams of air, the pressure and quantity of air guidedto the respiratory means can be reduced significantly compared with thesupplied air pressure. Due to its simple and yet highly reliablestructure, this type of pressure reducing valve is appreciated not leastfor medical purposes such as CPAP treatment. It is however oftenexperienced that the excess stream or streams of air emitted from thevalve may cause an uncomfortable cooling and drying effect for thetreated individual and during longer treatment cycles, complicationsderiving from the cooling and drying may occur.

It is crucial to secure a constant pressure and flow of air which cannot“by accident” be adjusted as it may have serious consequences for thepatient, in particular when treating premature babies. Known valvescomprise the feature of allowing the flow to be adjusted on the valveitself, and as the valve often need to be positioned in close vicinityof the baby, this feature makes them unsuitable for use inCPAP-treatment of particular premature babies, as there is a risk ofadjustment “by accident”, e.g. if the baby touches the valve.

In the PCT publication WO 01/76658 there is disclosed a system fordelivering warm, humidified oxygen to a patient at low flow rate. Thesystem including a conduit having an inlet and an outlet, between theinlet and the outlet a flowpath extends through the wall for lettingoxygen out. A member is movably positioned over the flowpaths forproviding means for adjusting the flow of oxygen to the patient.

Other known devices for use within the respiratory field are disclosedin U.S. Pat. No. 5,937,851 A, U.S. Pat. No. 6,112,745 A, and DE 10121959A. However these documents relate to the exhaust of CO₂ rather than forproviding air or gas to a patient, and a fourth document, U.S. Pat. No.5,042,478, relates to a nasal adaptor device.

DESCRIPTION OF THE INVENTION

It is an object of the present invention to overcome the above-describeddisadvantages of the known pressure-reducing valves.

According to a first aspect, the present invention relates to a pressurereducing valve for nasal supplying of a flow of air to a patient, thevalve comprising a hollowed tubular member comprising; a high pressureair inlet end part, a low pressure air outlet end part opposite to saidinlet end part, an intermediate air venting part having perforation(s)for venting a constant and non-adjustable pressure and flow of air fromthe inner cavity of the tubular member into the ambient atmosphere, andwherein a shielding member is positioned above said perforation(s) forsecuring the perforation(s) from becoming obstructed and for directingthe air flow from said perforation(s) towards said air inlet end part.

The pressure and flow of air is constant and cannot be adjusted on thevalve itself for safety reasons, as it is i.e. very important to keep aconstant overpressure inside the lunges of the patient. The pressure andflow may of course be adjusted prior to entering the valve, butpreferably not at a location where there is a possibility of adjustment“by accident” which may have serious consequences for the patient.

Due to the arrangement of the perforations, an excess stream of air,i.e. a stream of air passing through the air venting part, is guided ina direction opposite the direction of the stream of air which is usedfor the treatment, i.e. the stream which is guided to the respiratorytract. Accordingly, the valve supports an arrangement wherein one streamof air is guided in one direction e.g. to a set of nasal prongs andother streams of air is blown in a direction facing away from thisdirection.

Upon suitable fitting of the valve with respect to nasal prongs etc.,the air from the air venting part is blown in a direction facing awayfrom the individual receiving the treatment. The valve is, at one end,connected to the gas-conveying conduit supplying pressurised gas. Fromthis end, the supplied gas is split into a first flow of gas conveyed tothe low pressure outlet and a second flow of gas conveyed to the ambientatmosphere, the two gas-flows being directed in opposite directions, or,at least the second flow of gas is directed in the direction towards thehigh pressure air inlet.

The valve is preferably provided in the form of an annular or tubularmember defining a conduit between the high pressure air inlet and a lowpressure air outlet. Between the high pressure air inlet and the lowpressure air outlet, one or more air venting parts, i.e. parts forventing air to the ambient atmosphere may be defined. The air ventingpart or parts may be provided in the form of perforations of the wall ofthe tubular body, e.g. in the form of one or more air passages, such asthrough-going holes, i.e. holes extending from the conduit to anexterior surface of the annular or tubular member. On the exteriorsurface of the member, the air/gas flowing through the air ventingpart(s) is guided in a direction towards the high pressure air inlet.The through-going holes, i.e. the air venting part may extend radiallyfrom the conduit and may be provided, e.g. by drilling one or more holesin the side wall of the tubular member.

As an example, the hole(s) may be drilled throughout the side wall sothat a first part of the supplied gas can flow through the conduit fromthe high pressure air inlet to the low pressure air outlet, e.g. tonasal prongs while a second part of the supplied gas can flow throughthe through-going holes to the ambient atmosphere. At the point wherethe through-going holes reaches the outer surface of the tubular member,the flow of the second part of the supplied gas is turned into adirection opposite the direction of the first flow direction.

The tubular member is provided with a shielding member, (e.g. sleeve orcuff), surrounding the air venting part for shielding the perforationsand defining a space between the outer peripheral surface of the airventing part and the inner peripheral surface of the shielding member.The space may then be closed at a first end opposing the air outlet endpart and open at an opposite second end part opposing the air inlet end.The shielding member thus in co-operation with the tubular member formsa flow channel for the air being released to the ambient atmosphere.

As an example, the shielding member may be a tubular, hollow body withan internal diameter or clearance, which exceeds the external diameterof the tubular member so that a circular flow passage is defined thereinbetween. In one end, the cap seals against the outer surface of thetubular member towards the outlet end thereof. In the other end, thepassage defined between the inner surface of the cap and the outersurface of the tubular member is open to the ambient atmosphere.Accordingly, gas entering through the through-going holes is guidedthrough the circular flow passage from which passage it can only escapein a direction opposite the low pressure air outlet of the valve, i.e.in a direction facing away from the individual.

The shielding member may comprise a capsule-like member to be attachedto the tubular member, the capsule having an internal peripheral portionwith a flange section for shielding the perforation(s) and an attachmentsection for attaching it to the tubular member. The radial size of theflange section is larger than the radial size of the part of the tubularmember comprising the perforation(s) whereas the radial size of theattachment section being equal to or smaller than the radial size of apart of the tubular member located between the perforation(s) and theair outlet.

Preferably, the radial sizes of the integrated unit and the attachmentsection of the shielding member, respectively, are adjusted so that theshielding member is fitted to the integrated unit by interferencefitting and so that no air can escape through the fitting area towardsthe low pressure outlet. An O-ring may also be provided between theattachment section and the integrated unit, and/or there may be a grooveand tongue connecting there between.

According to a preferred embodiment of the invention, the air inlet andoutlet part, and the intermediate air venting part form an integratedunit, e.g. a one piece moulded tubular body of revolution. By having anintegrated unit it provides that movable parts are avoided which couldworsen the functionality of the valve. A particularly cost efficientvalve may be made from two individually injection-moulded plastics ormetallic parts, and wherein also the perforations in the venting partmay be provided in the mould, e.g. by means of special designed cores inthe mould.

A first of the parts may be an inner tubular body with a bore extendinglongitudinally between the high pressure air inlet and the low pressureair outlet. The tubular member may be provided with a number ofthrough-going radially extending holes, i.e. holes extendingperpendicularly to the first flow passage. A second of the parts may bean outer tubular cap. The shielding member is adapted in one end to sealagainst the outer surface of the tubular member whereas the other end isprovided with a radial size allowing gas to escape between an innersurface of the cap and an outer surface of the tubular member, when thecap is attached to the tubular member.

The perforated area of the valve may extend throughout or substantiallythroughout the inner cavity of the valve, thus making the air ventingpart adapted to vent the major part of the air flowing through the innercavity of the valve.

Moreover, the inner cavity and the perforation(s) of the air ventingpart could be shaped and dimensioned so as to reduce the air inletpressure from an overpressure of several bars to an overpressure of afraction of a bar. In particular, the dimensions of the high pressureinlet, the low pressure outlet, the air venting part and theperforations should be selected so that the air inlet pressure isreduced from the regular gas pressure supplies, i.e. normally 5-7 baroverpressure to the equivalence of 2-7 cm water column overpressure.

It may be an advantage to provide the shielding member as a separatepart attached to the integrated unit in order to allow inspection of theventing part.

The integrated unit may form an external peripheral portion with astepped configuration or with a flange, and the shielding member maythen easily be positioned on the integrated unit by sliding the memberonto the integrated unit until it engages a step or the flange of theperipheral portion of the integrated unit. In order to make the jointbetween the integrated unit and the shielding member (i.e. theattachment section of the shielding member) at least substantiallyairtight, the joined edges of at least one of the two parts may beprovided with a surface with sealing characteristics. As an example, theinner surface of the attachment section of the shielding member part maythus be provided with a soft and resilient material, e.g. provided on acircumferentially and radially inwardly extending flange adapted to sealagainst the outer surface of the integrated unit. Alternatively, theouter surface of the integrated unit may be provided with such amaterial at least in the step or on the flange.

The flow of air from the inner cavity may provide an even bettersecuring of the shielding member to the integrated unit, as the flow ofair coming through the perforations provides a force (pressure)substantially perpendicular on the inner surface of the shielding memberwhich thus provides a moment on the member so that the attachmentsection is pressed towards to outer surface of the integrated unit.

In order to support easy fitting of the valve for use in CPAP treatmentor for treatment of sleep apnea or for similar treatment, the lowpressure air outlet may be provided with a flange for connecting a nasalprong section. Alternatively, the low pressure air outlet may simply beformed as a set of nasal prongs allowing the air supply valve to beinserted directly into the nostrils.

During CPAP treatment of premature babies, the pressure reducing valvemust be worn by the treated individual in relatively close vicinity tothe respiratory organs. It may be positioned between 1-10 centimetresfrom the respiratory organs, preferably 3-4 centimetres from therespiratory organs. Accordingly, the weight of the valve is importantfor the well-being of the treated individual. Therefore, the weight maybe between 0,5-10 grams, preferably 1,5 gram. Accordingly, the valve maypreferably be made from a plastic material such as a thermoplast, whichfurther provides that the patient can keep the valve on during scanningdue to the translucent properties of plastic. In order to reduce themanufacturing costs, the valve may be made in one or two pieces byinjection moulding.

The valve often needs to be positioned close to the baby in the couveuse(incubator), and thus the baby might get in touch with the valve. As itis very important that the valve delivers a constant pressure and flowof air the valve must be construed so that it is insensitive againstexternal forces and other influences that could change the deliveredflow of air by mistake. Therefore, the shielding member is preferablyfixed attached to the tubular member so as to prevent the holes in theventing part to become obstructed, and thus secures a non-fluctuatingpressure and flow of air.

Furthermore due to the fixed attachment of the shielding member, thevalve can be used as a plug and play valve, thus an additional advantageis that it saves time for the personal working with the equipment.

The venting part may comprise one or a plurality of perforations.Preferably, the perforations of venting part comprise four air passagesdistributed around the circumference of the tubular member. The airpressure acting on the inner peripheral surface of the shielding membershould preferably be evenly distributed in order to avoid pressuredifference around the circumference thereof. Thus, the distribution ofthe perforations depends on the diameters of the perforations, so if thefour passages have different diameter, they must be distributed unevenlyaround the circumference. Preferably, the passages are even distributedso that the angle between the centre lines of the air passages issubstantially 90°, and the diameter of the one pair of oppositelyarranged air passages may be different from the diameter of the otherpair of oppositely arranged air passages. The diameter of theperforation(s) is preferably between 1-10 mm, such as 2-9 mm, such as3-8 mm, such as 4-7 mm, such as 5-6 mm.

The diameter of the inlet end part may be between 4-8 mm, preferably 6mm, and the diameter of the outlet end part is between 2-5 mm,preferably 3 mm.

The inner cavity and the perforation(s) of the air venting part may beshaped and dimensioned so as to reduce an air inlet overpressure of 6-7bars to an air outlet overpressure of a few cm water column, such as 1-8cm, such as 2-7 cm, such as 3-6 cm, such as 4-5 cm.

The distance between the outer surface of the air venting part and theinner surface of the shielding member is between 0.5-5 mm, preferably 1or 2 mm. The air venting part is adapted to vent preferably 50% or moreof the air flowing through the inner cavity of the valve into theambient atmosphere.

The cross-section of the pressure reducing valve and the shieldingmember may have any shape, such as quadrangular or triangular or oval,but preferably they have a substantially circular cross-section.

Preferably the pressure-reducing valve according to the invention isdisposable, and it may be pre-mounted in a “set” with an air supply tubeconnected to the high pressure inlet and maybe also with said nasalprong section connected to the low pressure outlet. The integrated unitmay be moulded (injection moulded) together with the nasal prong sectionso as to provide one single moulded unit comprising the valve and thenasal prong. Preferably, the integrated unit and the nasal prong sectionis made of different type of material, respectively. The integrated unitmay be made from unplasticised PVC (poly-vinyl-chloride) orpolypropylene, while the nasal prong section may be made from soft PVCor silicone materials. When moulding the integrated unit together withthe nasal prong section, it is preferred to have two mould-inlets eachof the moulded parts.

According to a second aspect, the present invention relates to a methodof providing gas to a CPAP valve, said method comprising conveying gasunder pressure from a gas supply to at least two gas conveying passages,one passage extending towards an outlet in a first direction and theother passage extending towards an outlet in a direction oppositely inrelation to the first direction.

The invention further relates to a method of providing gas to a CPAP(Continuous Positive Airway Pressure) valve, said method comprisingconveying gas under a first pressure from a gas supply through a valveaccording to the first aspect of the invention.

According to a third aspect, the present invention relates to a tubularair supply device defining an inner cavity therein and comprising a highpressure air inlet end part, an opposite low pressure air outlet endpart, an intermediate air venting part for venting air from the innercavity into the ambient atmosphere and air flow deflecting means fordirecting air flows from the air venting part towards the air inlet end.

The air venting part may be a perforated wall part, and the perforatedwall part may be an annular wall part.

The air flow deflecting means may comprise a sleeve or cuff surroundingthe air venting part and defining a space between the outer peripheralsurface of the air venting part and the inner peripheral surface of thesleeve or cuff, said space being closed at a first end opposing the airoutlet end part and open at an opposite second end part opposing the airinlet end.

Preferably, the air inlet part, the air outlet part, and theintermediate air venting part form an integrated unit, and theintegrated unit may be a tubular body of revolution.

The inner cavity and the air vents of the air venting part may be shapedand dimensioned so as to reduce the air inlet pressure from anoverpressure of several bars to an overpressure of a fraction of a bar.The air venting part may be adapted to vent the major part of the airflowing through the inner cavity of the device.

The sleeve or cuff may be a separate part attached to the integratedunit.

The integrated unit may form an external peripheral portion intermediatethe high pressure air inlet end part and the low pressure air outlet,said external peripheral portion comprising a stepped configuration or aflange adapted to position the sleeve or cuff.

The sleeve or cuff part may comprise an internal peripheral portion witha first section and a second section, the radial size of the firstsection being larger than the largest radial size of the integrated unitwhereas the radial size of the second section being smaller than theradial size of the largest radial size of the integrated unit.

The low pressure air outlet may be adapted with a flange for connectinga nasal prong section, and the low pressure air outlet may beconstituted by a nasal prong section having first and second nasal pronggas outlets. The sleeve or cuff part may be a tubular body ofrevolution.

It should be understood that any combination of the features and aspectsmentioned is possible within the scope of the present application.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the invention will now be described in detailswith reference to the drawings in which:

FIG. 1 shows a side view of a first part of a valve according to thepresent invention,

FIG. 2 shows the first part of FIG. 1, seen from the high pressure airinlet,

FIG. 3 shows a side view of a second part of a valve according to thepresent invention,

FIG. 4 shows the second part of FIG. 3, seen from an end thereof, which,when attached to the first part, is towards the high pressure air inlet,

FIG. 5 shows a perspective view of a valve according to the presentinvention, and

FIG. 6 shows another perspective view of the valve of FIG. 5.

FIG. 7 shows a schematic view of the valve in combination with an airsupply tube, and

FIG. 8 shows a schematic view of the valve in combination with both anair supply tube and a nasal prong section.

As shown in FIG. 1, a first part of a valve according to the presentinvention is an integrated unit comprising an oblong tubular member 1provided with an internal flow passage 2. In FIG. 1, the passage issymbolised by the to dotted lines 5. The flow passage extends from ahigh pressure air inlet 3 to a low pressure air outlet 4. Intermediatebetween the inlet and the outlet, an air venting part is formed byperforation of the tubular member. In FIG. 1, the perforation is formedas four radially, throughout extending bore holes 6 allowing air toescape from the internal flow passage (inner cavity) to the ambientatmosphere (two of the bore holes is symbolised by the dotted lines 7).

As shown in FIG. 1, the oblong tubular member 1 may preferably have astepped configuration with sections 8, 9, 10 and 11 having differentexternal cross sectional sizes or diameters. Likewise, the flow passagemay be split into sections having different cross-sectional sizes ordiameters. At the high pressure inlet and/or at the low pressure airoutlet, one or more resilient o-rings 20 may support air tightconnection between the integrated unit and an air-supply hose and/ornasal prongs, respectively.

In FIG. 2, it is seen that the integrated unit is a tubular body ofrevolution.

In FIG. 3, the shielding member in the form of a second part 12, i.e. asleeve or cuff part of the valve, is shown. The second part is providedwith an elongated body having a pair of axially spaced, opposed ends13,14. At one end 13, the second part is adapted to seal along an outersurface of the integrated unit part—an O-ring may be provided forsealing between said second part and the tubular member. At the otherend 14 the second part in combination with the integrated unit, forms anoutlet for the gas flowing through the air venting parts (perforations).The surface part 19 is adapted to slide against the surface part 17 ofthe integrated unit until the surface part 18 abuts against the surfacepart 16 of the integrated unit.

The stepped configuration of the external surface of the integrated unitwill allow the second part to be positioned easily on to the integratedunit. As an example, one section of the first part may be provided withan external diameter allowing one section of the second part to beattached in a gas sealing engagement. Another section may be providedwith a larger external diameter thus preventing the second part to slideover this section.

FIG. 5 shows a perspective view wherein the second part is attached tothe first part.

FIG. 6 shows another perspective view wherein the passage definedbetween the integrated unit and the second part is shown. As shown, airentering through the high pressure air inlet 3 may flow in asubstantially linear flow direction towards the low pressure air outlet4, to which end nasal prongs or similar means for leading a flow of gasto the nostrils of a treated subject may be attached. Alternatively,nasal prongs may be an integrated part of the low pressure air outlet 4.Intermediate the two ends, a venting part may lead gas to the ambientatmosphere, which gas, by the second part 12 will be directed in adirection towards the high pressure gas inlet 3. In a preferredembodiment, the valve is provided with connecting flanges in one or bothof the low and high pressure ends. The connecting flanges may e.g. beprovided with one or more circumferentially extending protrusions, e.g.in the form of one or more O-shaped rubber rings. The high pressure endmay be coloured in one colour and the low pressure end in anothercolour, thus allowing easy and safe orientation of the valve during theassembly with the gas supplies and the respiratory means. In FIG. 6, theflow channel 15 defined between the integrated unit or oblong body 1 andthe second part 12, is clearly seen. The channel directs the airreleased via the air venting part from the inner cavity to the ambientatmosphere, in a direction opposite the direction of the low pressureair outlet.

FIG. 7 shows a schematic view of the valve in combination with an airsupply tube 21. The air supply tube 21, connected to an air supplier inits inlet end, is connected to the high pressure inlet 3 of the valve.The connection of the tube is sealed by means of the moulded groovesand/or O-rings 20, but the connection may be sufficiently tight withoutsaid grooves or O-rings. The shielding member 12, the perforations 6 andthe outlet 4 is also shown.

FIG. 8 shows a schematic view of the valve in combination with both anair supply tube 21 and a nasal prong section 22. The prong section isconnected to the low pressure outlet end 4 of the valve. The prongsection comprises two nasal prong air outlets 23 to be inserted into thenostrils. The valve and nasal prong section may be moulded together asone single unit.

1. A non-adjustable pressure reducing valve for nasal supplying of aflow of air to a patient, said valve comprising; a hollowed tubularmember defining an internal continuous flow passage extending from ahigh pressure air inlet end part, adapted to receive a flow of air froman air supplying conduit, to a low pressure air outlet end part oppositeto said inlet end part and adapted to be connected to respiratory meansfor delivering a first part of said flow of air to the patient, and anintermediate air venting part having perforation(s) for venting a secondpart of said flow of air from said flow passage of the tubular memberinto the ambient atmosphere, and a shielding member being attached tothe tubular member such that a space is defined between an outer surfaceof the air venting part and an inner surface of the shielding member inorder to provide a shield above said perforation(s), said space beingclosed at the end towards the air outlet end part and open at theopposite end towards the air inlet end for directing the second part ofthe air flow from said perforations towards said air inlet end part. 2.A valve according to claim 1, wherein the air inlet part, the air outletpart and the intermediate air venting part form an integrated unit.
 3. Avalve according to claim 1, wherein the valve is made in one piece.
 4. Avalve according to claim 1, wherein the shielding member comprises acapsule-like member to be attached to the tubular member, the capsulehaving an internal peripheral portion with a flange section forshielding said perforation(s) and an attachment section for attaching itto the tubular member, the radial size of the flange section beinglarger than the radial size of the part of the tubular member comprisingthe perforation(s) whereas the radial size of the attaching sectionbeing equal to or smaller than the radial size of a part of the tubularmember located between the perforation(s) and the air outlet.
 5. A valveaccording to claim 1, wherein the tubular member comprises an externalperipheral portion between the high pressure air inlet end part and thelow pressure air outlet, said external peripheral portion comprising astepped configuration or a flange for receiving and holding saidattachment section of the shielding member.
 6. A valve according toclaim 1, wherein the shielding member is a tubular body of revolutionsurrounding the air venting part.
 7. A valve according to claim 1,wherein the shielding member is a separate part attached to the tubularmember.
 8. A valve according to claim 1, wherein the shielding member isfixed attached to the tubular member.
 9. A valve according to claim 1,wherein the distance between said outer surface of the air venting partand said inner surface of the shielding member is between 0.5-5 mm, suchas 1 or 2 mm.
 10. A valve according to claim 1, wherein the diameter ofthe inlet end part is 4-8 mm, such as 6 mm.
 11. A valve according toclaim 1, wherein the diameter of the outlet end part is 2-5 mm, such as3 mm.
 12. A valve according to claim 1, wherein the perforationscomprise four air passages substantially even distributed around thecircumference of the tubular member.
 13. A valve according to claim 12,wherein the angle between the centre lines of the air passages issubstantially 90°.
 14. A valve according to claim 13, wherein thediameter of the one pair of oppositely arranged air passages isdifferent from the diameter of the other pair of oppositely arranged airpassages.
 15. A valve according to claim 1, wherein the diameter of theperforation(s) is between 1-10 mm, such as 2-9 mm, such as 3-8 mm, suchas 4-7 mm, such as 5-6 mm.
 16. A valve according to claim 1, wherein thevalve is disposable.
 17. A valve according to claim 1, wherein the innercavity and the perforation(s) of the air venting part are shaped anddimensioned so as to reduce an air inlet overpressure of 6-7 bars to anair outlet overpressure of 2-7 cm water column.
 18. A valve according toclaim 1, wherein the air venting part is adapted to vent 50% or more ofthe air flowing through the inner cavity of the valve into the ambientatmosphere.
 19. A valve according to claim 1, wherein the low pressureair outlet comprise a flange for connecting a nasal prong sectionthereto.
 20. A valve according to claim 1, wherein the low pressure airoutlet is constituted by a nasal prong section having first and secondnasal prong air outlets.
 21. A method of providing gas to a CPAP(Continuous Positive Airway Pressure) valve, said method comprisingconveying gas under a first pressure from a gas supply to at least twogas passages, one passage extending towards an outlet in a directiontowards a patient and the other passage extending towards an outlet inan opposite direction so as to reduce the pressure of the air coming outof the outlet to a pressure level below said first pressure.
 22. Amethod of providing gas to a CPAP (Continuous Positive Airway Pressure)valve, said method comprising conveying gas under a first pressure froma gas supply through a valve comprising: a hollowed tubular memberdefining an internal continuous flow passage extending from a highpressure air inlet end part, adapted to receive a flow of air from anair supplying conduit, to a low pressure air outlet end part opposite tosaid inlet end part and adapted to be connected to respiratory means fordelivering a first part of said flow of air to the patient, and anintermediate air venting part having perforation(s) for venting a secondpart of said flow of air from said flow passage of the tubular memberinto the ambient atmosphere, and a shielding member being attached tothe tubular member such that a space is defined between an outer surfaceof the air venting part and an inner surface of the shielding member inorder to provide a shield above said perforation(s), said space beingclosed at the end towards the air outlet end part and open at theopposite end towards the air inlet end for directing the second part ofthe air flow from said perforations towards said air inlet end part.